The present invention is directed to a seal for a hydraulic component. More particularly, the present invention is directed to a wiper seal for a rod in a hydraulic component.
Many work machines, such as tractors, excavators, loaders, and other earth moving equipment, utilize hydraulic components to generate the force required to accomplish their tasks. These hydraulic components, which include, for example, hydraulic actuators, hydraulic cylinders, and fluid motors, typically include two fluid chambers disposed on opposite sides of a moveable element. Pressurized fluid is introduced into one of the fluid chambers, which causes the moveable element to move relative to the hydraulic component housing.
The moveable element is usually connected to a work implement on the work machine through a rod or shaft. Typically, each hydraulic component includes a sealing arrangement that prevents pressurized fluid from leaking from the fluid chambers of the hydraulic component during use. One such sealing arrangement for a hydraulic cylinder is described in U.S. Pat. No. 6,116,613.
A sealing arrangement for a hydraulic component may include a series of seals. In one such sealing arrangement for a hydraulic cylinder, three seals are disposed in the cylinder head to engage the shaft proximate the exit point of the shaft. The cylinder head typically includes a series of annular grooves, or counter bores, that are configured to receive each of the three seals. The first seal, which is placed closest to the pressurized fluid, is known as a buffer seal. The buffer seal forms a high pressure seal with the shaft to prevent the pressurized fluid from escaping the hydraulic cylinder. Due to the high operating pressures of the hydraulic cylinders, however, some of the pressurized fluid will leak through the buffer seal.
The second seal, which is placed on the opposite side of the buffer seal from the fluid chamber is known as a xe2x80x9cU-cupxe2x80x9d seal. This seal typically has a notch or groove that forms a xe2x80x9cUxe2x80x9d shape. This seal provides a second seal to prevent the fluid that has leaked through the buffer seal from escaping the hydraulic cylinder. This fluid is captured in a gap between the buffer seal and the xe2x80x9cU-cupxe2x80x9d seal and in the notch or groove in the seal. When operating conditions permit, the buffer seal allows the captured fluid to bypass the buffer seal and return to the system.
The third seal, or the outermost seal, is known as a wiper seal or, alternatively, as a rod seal or a rod scraper seal. This seal prevents dirt or debris from entering the system and contaminating the fluid. Some wiper seals may also wipe any remaining fluid from the surface of the shaft. The fluid removed from the surface of the shaft is collected in a gap between the xe2x80x9cU-cupxe2x80x9d seal and the wiper seal. Other wiper seals may leave a thin film of fluid on the surface of the shaft as the shaft is extended.
To prevent dirt or debris from entering the system, a lip of the wiper seal must remain in contact with the surface of the shaft. Accordingly, the wiper is configured to have a close fit with the surface of the shaft so that the lip exerts a relatively high pressure on the surface of the shaft. After extended use, the pressure of the lip on the surface of the shaft may create wear marks, such as grooves, in the surface of shaft. Excessive wear marks on the shaft may reduce the effectiveness of the sealing arrangement and allow fluid to leak from the housing.
In addition, the lip of the wiper seal may not create a uniform seal around the surface of the shaft. In some cases, this may result in an uneven layer of fluid remaining on the surface of the shaft as the shaft extends from the cylinder head. This uneven distribution of fluid on the shaft may give the false impression that the sealing assembly is leaking and is need of repair.
The wiper seal of the present invention is directed to solving all or some of the problems set forth above.
One aspect of the invention is directed to a wiper seal for a hydraulic component. The wiper seal includes a support member and a body portion. The support member includes a first leg having an inner surface, a first end, and a second end. The first leg extends substantially parallel to a reference axis. A second leg having an outer surface extends substantially perpendicular to the reference axis from the first end of the first leg. The body portion defines an opening therethrough and includes an outer peripheral surface configured to receive the inner surface of the first leg of the support member, a first radial face extending substantially coplanar to the outer surface of the second leg, an inner surface disposed at an angle relative to the reference axis and extending to a lip adjacent the first radial face, and a second radial face extending generally perpendicular to the reference axis from the second end of the first leg of the support member. The first radial face includes a first cutout and the second radial includes a second cutout.
According to another aspect, the present invention is directed to a hydraulic component that includes a housing that defines at least one chamber configured to hold a pressurized fluid and has a head that defines an opening. A rod having a surface is disposed for sliding movement in the opening of the housing. A wiper seal is disposed in the housing and includes a support member and a body portion. The support member includes a first leg having an inner surface, a first end, and a second end. The first leg extends substantially parallel to a reference axis. A second leg having an outer surface extends substantially perpendicular to the reference axis from the first end of the first leg. The body portion defines an opening configured to receive the rod and includes an outer peripheral surface configured to receive the inner surface of the first leg of the support member, a first radial face extending substantially coplanar to the outer surface of the second leg, an inner surface disposed at an angle relative to the reference axis and extending to a lip adjacent the first radial face and configured to engage the surface of the rod, and a second radial face extending generally perpendicularly to the reference axis from the second end of the first leg of the support member. The first radial face includes a first cutout and the second radial includes a second cutout.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.